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<b><font color="#cc0000">
NOTE:
Deprecation of the technologies described here has been announced
for platforms other than ChromeOS.<br/>
Please visit our
<a href="/native-client/migration">migration guide</a>
for details.
</font></b>
<hr/><section id="sandbox-internals">
<h1 id="sandbox-internals">Sandbox Internals</h1>
<p>The sandbox internals documentation describes implementation details for
Native Client sandboxing, which is also used by Portable Native
Client. These details can be useful to reimplement a sandbox, or to
write assembly code that follows sandboxing rules for Native Client
(Portable Native Client does not allow platform-specific assembly code).</p>
<p>As an implementation detail, the Native Client sandboxes described here
are currently used by Portable Native Client to execute code on the
corresponding machines in a safe manner. The portable bitcode contained
in a <strong>pexe</strong> is translated to a machine-specific <strong>nexe</strong> before
execution. This may change at a point in time: Portable Native Client
doesn&#8217;t necessarily need these sandboxes to execute code on these
machines. Note that the Portable Native Client compiler itself is also
untrusted: it too runs in a Native Client sandbox described below.</p>
<p>Native Client has sandboxes for:</p>
<ul class="small-gap">
<li><a class="reference internal" href="/native-client/reference/sandbox_internals/arm-32-bit-sandbox.html#arm-32-bit-sandbox"><em>ARM 32-bit</em></a>.</li>
<li>x86-32: the original design is described in <a class="reference external" href="http://research.google.com/pubs/archive/34913.pdf">Native Client: A Sandbox
for Portable, Untrusted x86 Native Code</a>, the current
design has changed slightly since then.</li>
<li><a class="reference internal" href="/native-client/reference/sandbox_internals/x86-64-sandbox.html#x86-64-sandbox"><em>x86-64</em></a>.</li>
<li>MIPS32, described in the <a class="reference external" href="https://code.google.com/p/nativeclient/issues/attachmentText?id=2275&amp;aid=22750018000&amp;name=native-client-mips-0.4.txt">overview of Native Client for MIPS</a>,
and <a class="reference external" href="https://code.google.com/p/nativeclient/issues/detail?id=2275">bug 2275</a>.</li>
</ul>
</section>

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